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What is the e.firma?

The e.firma, formerly known as Firma Electrónica Avanzada or Advanced Electronic Signature, also known as FIEL, is the most secure digital identification mechanism with the highest legal validity in Mexico. It is issued by the Tax Administration Service (also known as  SAT in Mexico) and is designed to guarantee the identity of a taxpayer in electronic operations.

Cincel integrates the use of the e.firma to offer the maximum level of certainty and legal security in your most important contracts and documents.

 

Legal basis and validity

The e.firma is not just a technological tool; it is a figure with solid legal backing. According to Article 17-D of the Fiscal Code of the Federation (Mexico), the e.firma:

  • Substitutes the autograph (handwritten) signature.
  • Produces the same legal effects as the autograph signature.
  • Guarantees the integrity and non-alteration of the document.
  • Ensures non-repudiation, which means that the signer cannot deny having signed the document.

For these reasons, the e.firma is considered a Firma Electrónica Avanzada, the gold standard for the validation of digital agreements in Mexico.


Components of the e.firma

Your e.firma consists of three inseparable elements that guarantee its security and ownership:

  1. Digital Certificate (.cer): A public file that functions as your digital identity credential. It allows third parties to verify that you are who you claim to be.
  2. Private Key (.key): A secret and encrypted file that only you possess. It is the tool that allows you to "stamp" your signature on a digital document, proving your consent.
  3. Private Key Password: An access code that protects your .key file, ensuring that no one else can use it, even if they obtain the file.

❗ ️Important: To protect your information, Cincel never stores your .cer, .key files or your password. You must load them every time you sign a document, guaranteeing that only you have control over your e.firma.

 

When should the e.firma be used in Cincel?

While Cincel's digital autograph signature is legally valid for most agreements, it is recommended to use the e.firma for high-value or high-risk documents, such as:

  • Purchase and sale contracts for real estate or high-value assets.
  • Credit contracts and other financial instruments.
  • Corporate agreements or assembly minutes.
  • Any document that, by its nature, requires the maximum presumption of integrity and authorship between the signing parties and before the authorities.


Important Considerations:

  • Validity: To be able to sign in Cincel, your e.firma must be valid. It is not possible to use an expired certificate.
  • Legal Entities: It is possible to sign with the e.firma of a legal entity. However, it is crucial to verify that the legal representative associated with that e.firma has the legal powers to enter into the act in question.
  • Privacy: The SAT has no access or visibility of the documents you sign with your e.firma through Cincel. The cryptographic validation process is performed without exposing the content of your agreements.